Domestic appliance



March 25, 195s G. B. LONG DOMESTIC APPLIANCE 4 Sheets-Sheet l T Ill INVENTOR. 3. [0 257 Filed July 1, 1955 Geog: BY

' March 25, 1958 G. B. LONG 2,828,404

DOMESTIC APPLIANCE Filed July 1, 1955 4 Sheets-Sheet 2 [N V EN TOR.

March 25, 1958 3, LONG 2,828,404

DOMESTIC APPLIANCE Filed July 1, 1955 4 Sheets-Sheet 5 Kw; /za i E 7 2 7 n a; I 12? L2 My 5 LI INVENTOR.

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March 25, 1958 G. B. LONG DOMESTIC APPLIANCE 4 Sheets-Sheet 4 Filed July 1, 1955 INVENTOR. 11 2! DOMESTIC APPLIANCE George B. Long, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application July 1, 1955, Serial No. 519,383

Claims. (Cl. 219-37) This invention relates to a domestic appliance and more particularly to domestic electric ranges.

Vapors, smoke and fumes are often formed in an oven during broiling and baking. These contaminate the walls of the oven, the vents and also the walls of the kitchen.

It is an object of this invention to provide a simple, economical and practical apparatus for keeping objectionable vapors, smoke and fumes from being discharged from a two oven range into the kitchen.

It is another object of this invention to provide an arrangement whereby a single oxidation catalyst may be used to eliminate smoke and fumes and to assist in'the heating of two oven compartments simultaneously or alternately.

it is another object of this invention to provide an arrangement wherein an oxidation catalyst may be continued in operation automatically for a limited period following the discontinuance of heating the oven.

It is another object of this invention to provide an arrrngement wherein the bake heater as well as the oxidation catalyst are located in a recirculation duct in communication with the oven.

These and other objects are obtained in the forms shown in the drawings in which two oven compartments are located side by side in a domestic electric range. The upper and lower portions of each of these compartments are connected through openings provided with dampers with the upper and lower portions of an upwardly extending duct provided at the back of the range. The duct contains a wire grid extending across the duct from side to side. This wire grid has a coating of an oxidation catalyst. It is connected to the oven circuit so that it is heated to a suitable temperature whenever the oven is being used. A fan energized coincidentally with the energization of the oven is provided for circulating and recirculating the atmosphere through the duct and the ovens. The atmosphere of the ovens is thereby kept substantially free of smoke fumes and vapors and the heat given off by the wire is carried back to the compartments to assist in the heating thereof. A thermostat is provided for controlling the temperature of the coated wire.

In another form of the invention, the baking heater is associated in the same duct with the catalyst so that the ovens are heated by convection. A time delay switch, operated to closed position in response to the energization of either the baking or broil heaters, energizes the catalyst heaters throughout the heating period and for a predetermined period of time thereafter.

Further objects and advantages or" the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings: Figure l is a diagrammatic vertical sectional view of a two-unit electric oven disclosing one embodiment of my invention taken along the line 1--1 of Figure 2;

United States Patent 0 'ice Figure 2 is a diagrammatic horizontal sectional view taken along the line 2-2 of Figure 1;

Figure 3 is a diagrammatic vertical sectional view taken along the line 3-3 of Figure 2;

Figure 4 is an enlarged top view of the oxidation catalyst;

Figure 5 is a fragmentary sectional view similar to Figure 1 showing the controls and dampers shifted to connect the duct to the left compartment;

Figure 6 is a fragmentary vertical sectional view similar to Figure 5 showing the controls and dampers arranged to connect the right compartment to the duct;

Figure 7 is a vertical diagrammatic sectional view showing a modified form of the invention applied to a twooven range;

Figure 8 is a wiring diagram for the range shown in Figures 1 to 6;

Figure 9 is a diagrammatic vertical sectional view looking from the rear showing another form of the invention applied to a two oven range;

Figure 10 is a wiring diagram for the modification shown in Figure 9; and

Figure 11 is an enlarged view showing the time delay switch embodied in Figure 10.

Referring now to the drawings, there is. shown a twooven domestic range 20 having walls 22 and a door 24 enclosing-a left compartment and walls 26 and a door 28 enclosing a right compartment. The left and right oven compartments are each provided with a two-section upper heating unit designated 30 and 32. The adjacent side walls of each of the compartments are provided with upper outlet openings 38 and 40 connecting with the duct connector 42 provided between the walls. The lower portion of the adjacent side walls are provided with the outlet openings 44 and 46 communicating with the duct connectors 48.

As shown in Figures 2 and 3, at the rear of the left and right compartments there is provided a vertical duct 50. This vertical duct connects at the top through the openings 52 with the upper duct connector 42 and at the bottom through the openings 54 with the lower duct connector 48. Extending substantially completely across the duct is an oxidation catalyst unit 56. This unit 56 may be either self heated or externally heated and may be in the form of a grid or long wire. One example of such a unit is shown in Figure 4 which includes a rectangular metal frame 58 having transverse innercross members 60 of electrical insulating material upon which a fine Nichrome wire 62 is wound in closely spaced relation substantially from one side of the frame 58 to the other side thereof. This wire is provided with a coating of a highly active oxidation catalyst containing platinum and alumina. Preferably the wire contains nickel and 20% chromium and as much as 200 feet of this wire is used. it may be wound in two separate coils in two layers. it is preferably kept by a sufficient electrical current flow at a temperature of about 900 F. during operation. This temperature however may be varied between 500 F. and 1000" F. with varying but beneficial results.

To bring the atmosphere of the oven into contact with the oxidation catalyst 56, and to return the heat dissipated by the catalyst there is provided a fan 60 in the lower portion of the duct 50 immediately above the opening $4. This fan draws the atmosphere from either or both oven compartments in through the openings 38 and 40 into the upper duct connector 42, through the opening 52 down through the duct 50 and the oxidation catalyst 56 to the return opening 54 which permits the atmosphere to return through the duct connector 58 and the openings 44 and 46 to the two-oven compartments. As the vapors,

right oven compartment.

fumes, and smoke particles pass into contact with the oxidation catalyst 56, they are oxidized into water and carbon dioxide, removing substantially any trace of odor orsrnoke. in order to provide additional oxygen to accomplish the oxidation; the bottom of each of the doors elimination of smoke and fumes from both compartments. 'In this arrangement all of the openings connecting the compartments with the duct are completely open. When only one of the oven compartments is being used, it is desirable to shut off the other oven compartment from the duct system. To do this each oven is provided with an upper damper, 68 and 76, adapted to close the openings 38 and 4t? alternately. Each oven is also provided with a lower damper, 74 and 76, adapted to close the low openings 44 and 46 alternately. The dampers 74 and 78 are connected by a rod 76 to a slotted lever 78 pivoted at its center point to a bracket 86. This slotted lever '78 is provided with an upright handle 82 which can be shifted to the left as shown in Figure to allow the left compartment to be connected to the oxidation duct 50 'while the dampers 70 and 76 shut off the right compartment or to the right to connect the right compartment to the om'dation duct 50 while the dampers 68 and 74 shut off the left oven compartment as illustrated in Figure 6.

The duct St is also provided with a thermostat 84 immediately above the fan 60 to cut off the current through the coil 62 in the event that the temperature becomes too high. As shown in Figure 8, this thermostat 34 is connected in series with the coil 62. The fan 60 has its motor 86 beneath the duct 50 and connected in shunt with the thermostat S4 and the coil 62. The terminals of the thermostat 84, the coil 62 and the fan motor 86 are connected by the conductors 90 and 92 with the contacts 94 and 96 of the oven thermostat 98. These terminals are also connected by the conductors 121 with the contacts 123 and by the conductor 125 with the contact 126 of the thermostat 129. The thermostat 98 is controlled by the bulb 131 located in the left oven compartment while the thermostat 129 is controlled by the bulb 133 in the right oven compartment. The lower oven heating unit 34 is connected by the switches 135 and 137 to the conductors 9d and 92. These switches are open during broiling.

The upper unit 36 includes the heater section 139 and the heater section 141. One terminal of the section 139 is connected by the switch 143 to the conductor 90. One terminal of the section 141 is connected by the double throw switch 145 to either the conductor 95) or the conductor 92. The adjacent terminals of the heater section 139 and 141 are connected by the switch 147 with the conductor 92. With this arrangement the heater sections 139 and 141 may be connected in parallel with the conductors 19d and 192 for broiling and preheating while they may be connected in series across these conductors for baking. The heaters 32 and 36 are similarly connected to the conductors 121 and 125. The switches 24 and 123 are connected to the supply conductor L while the switches 96 and 127 are connected to the supply conductor L in Figure 7 a modified form of a two-oven range is shown in which a first set of walls 22% enclose a left oven compartment and a second set of walls 222 enclose the These compartments have inlet ventilating openings 224 and 226 adjacent the lower edge of the doors which may be similar to the doors and openings in Figures 1 to 6. Each of these compartments have outlet openings 228 and 230 connecting with an upwardly extending duct 232. This upwardly extending duct 232 connects with a horizontal duct 234 beneath the top 236 of the range 238. This horizontal duct 234 includes an element 240 like that shown in Figure 4 composed of Nichrome wire provided with an oxidation catalyst which includes platinum and alumina. A thermostat 242 is provided for controlling the temperature of the catalyst unit or element 245). The duct 234 connects to verticai duct 244 having a discharge opening 246 in the center of the surface heater 248. In this form, as the ovens are ventilated by the flow of air coming in through the lower openings 224 and 226 and flowing through the oven compartments to and through the open- 228 and 230 and through the ducts 232, 234 and 2 The smoke and fumes are removed from this air flow by the element 240 to prevent the kitchen from being filled with vapors andsmoke.

The oxidation catalyst 56 may include an outer coil wrapped over the inner coil 62 in spaced insulated relationship as shown in Figure 4 and provided with a separate set of terminals so that the coils may be used separately or in series or in parallel.

In the modification shown in Figure 9 the damper controls and the duct connections are substantially the same as shown in Figures 1 to 3, 5 and 6. The range 320 has the walls 322 enclosing a left compartment (viewed from the rear) designated by the reference character 324 and the walls 326 enclosing a right compartment 328. This form differs in that in each of these compartments there is a single upper broil heating unit 330 and 332 which may be in a single section. The feature of this range is that the compartments 324 and 328 have no lower heatin units. The objection to the lower heating unit is that they are exposed to spillage in the oven. For baking purposes the heat is supplied to either compartment by the heating unit 334 which is located within the rear duct 336 which connects to the top and bottom through damper controlled openings to the compartments 324 and 328. The atmosphere within either of the compartments is circulated over the heater 334 by the fan 338 driven by the electric motor 340. V F V In the upper portion of the duct there is provided two oxidation catalyst elements 342 and 344 which maybe combined into a single two-element unit like that shown in Figure 4. The element 344 alone is used for baking when less catalytic oxidation is required and when it is desired to keep the heat emitted at a minimum to prevent overshooting the desired baking temperature. Both catalytic elements may be used for broiling since the amount of smoke and fumes generated are greater during broiling and overshooting of the selected temperature is less objectionable than during baking. The broil unit 33% is connected through the switch 346, the conductor 343 and the thermostat contact 356 with the supply conductor L The other terminal of this broil unit 330 is connected by the switch 352 and the conductor 354 and the thermostatic switch 356 to the-supply conductor L The switch contacts 350 and 356 are operated by the hydraulic thermostatic system including the bellows 358 connected by. a capillary tube to the thermostat bulb 360 located in the compartment 324.

The right terminal of the broil unit 332 is connected by the switch 362, the conductor 364, the switch contacts 366 and the conductor368 with the supply conductor L The other terminal of the broil heater 332 is connected by the switch 370, the conductor 372, the switch contacts 374 and the conductor 376 to the supply concompartment 323.

The bake heater 334 is provided at each end with the double throw switches 382 and 384. The switch 382 alternately connects through the conductors 386 and 388 with the conductors 354 and 364. The switch 384 alternately'connects through the conductors 390 and 392 with the conductors 348 and 372. By this arrangement for baking purposes in either oven the baking heater 334 can be connected to be energized and controlled by the thermostatic switches of either oven. The dampers may be set to connect the duct 336 with either oven compartment 324 or 328 or both if the thermostats 358, 378 are set to the same temperature. The oxidation catalyst element 344 has one terminal connected to the heater 334 and the other terminal connected through the conductor 394 and the thermostat 396 to the neutral supply conductor N. The thermostat 396 is located in the duct 336 adjacent the oxidation catalyst for the purpose of preventing the catalyst from becoming overheated. It deenergizes the elements 342 and 344 when they reach a temperature of about 900 F.

During broiling, it is likely that the smoke, fumes and vapors will continue to be generated for a period of time after either or both broil heaters are deenergized. For this purpose a conductor 421 extends upwardly from the conductor 376 to a thermal time-delay switch 423 which is shown in diagrammatic enlarged form in Figure 11. This switch 423 provides a connection when closed through contacts 443-441 with the oxidation catalyst element 342 which connects through the conductor 425 to the thermostat 396 which in turn connects to the neutral supply conductor N. The switch 423 also connects through the contacts 465 and 467 and the conductor 427 to the fan motor 340 which in turn connects through the conductor 429 to the neutral supply conductor N. The conductor 427 also connects to the bake heater 334 and the catalyst element 344 so that the motor 340 will operate during baking.

The time-delay switch 423 includes a cantilever bimetal blade 431 having a suitable stationary anchorage 433 at one end and a C-shaped toggle spring 435 at the opposite end provided with a stationary pivoting anchorage 437. The anchorage 437 is located above the line of cantilever bi-metal so that the effect of the toggle spring in holding the bi-metal 431 in the open circuit position against the stop screw 439 is small compared to its elfect in holding the blade 431 in closed position against the contacts 441 and 467. The free end of the blade 431 carries the movable contacts 433 and 465. The blade 431 may also carry a mass 445 adapted to absorb heat to introduce additional timedelay. The blade 431 bows downwardly when heated by either or both of the heaters 447 or 449. The heater 447 has its terminals connected in shunt with a portion 451 of the broil heater 330. The heater 449 has its terminals connected in shunt with the portion 453 of the broil heater 332.

In this way the heater 447 will be energized to move the time-delay switch 423 to closed position whenever the broil heater 330 is energized to energize the oxidation catalyst element 342 as well as the fan motor 340. Likewise whenever the broil heater 332 is energized, the heater 449 will be energized to move the time-delay switch 423 to the closed position. When either of the broil heaters 330 or 332 is deenergized, the heaters 447 and 449 will likewise be deenergized. However the toggle spring 435 will have a force sufficient to hold the time-delay switch 423 in the closed position during the slow cooling of the bi-metal 431 so that the deenergization of the oxidation catalyst 342 will be delayed for as long as five or ten minutes following the deenergization of the broiling heaters. During this time the catalyst will continue to oxidize smoke and fumes which may be generated or which may be present after the deenergization of the broil heaters.

Although this modification has been shown as applied to a two oven range, it is also applicable to a single oven range merely by omitting the elements required by the second oven.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

1. A range including walls and a door enclosing an oven compartment, an upwardly extending duct having its upper and lower portions connected to the upper and lower portions of said compartment, a wire having an outer surface in the form of an oxidation catalyst located in said duct, fan means located in said duct for drawing atmosphere from said compartment through said duct in contact with said wire and returning the treated atmosphere to said compartment, said compartment being provided with an inlet opening for outside air and said duct being provided with an outlet opening for ventilating the oven compartment, electrical heating means for said oven compartment, means for electrically energizing said wire and said fan means, and temperature responsive means for controlling the energization of said wire.

2. A two oven range including a first set of walls and a first door enclosing a first oven compartment, a second set of walls and a second door enclosing a second oven compartment, an upwardly extending duct having its upper and lower portions connected to the upper and lower portions of each of said compartments, a wire having an outer surface in the form of an oxidation catalyst located in said duct, fan means for recirculating atmosphere from both of said compartments through said duct in contact with said oxidation catalyst and back to said compartments, said compartments each being provided with an inlet opening for outside air, said duct being provided with a discharge opening for discharging atmosphere to the outside, and means for heating said ovens and said wire.

3. A range including walls enclosing an oven compartment, a broil heating means in the top of said compartment, an upwardly extending duct connected at its upper and lower portions with the upper and lower portions of said compartment, a bake heating means located in said duct, a first oxidation catalyst provided with a first heating means, a second oxidation catalyst provided with a second heating means, fan means for recirculating atmosphere through said duct and compartment, means responsive to the energization of said broil heating means for energizing said fan means and said first and second heating means, and means responsive to the energization of said bake heating means for energizing said fan means and said first heating means.

4. A range including walls enclosing an oven compartment, heating means for said compartment, an oxidation catalyst associated with only said compartment for oxidizing smoke and fumes generated in said compartment, a catalyst heating means for said oxidation catalyst, switch means having time delayed operation for controlling the energization of said catalyst heating means, said switch means being operated in response to the energization of said compartment heating means to energize said catalyst heating means and being provided with a time delay arrangement for delaying the deenergization of said catalyst heating means for a period of time following the deenergization of said compartment heating means.

5. A two oven range including a first set of walls and a first door enclosing a first oven compartment, a second set of walls and a second door enclosing a second oven compartment, an upwardly extending duct having its upper and lower portions connected to the upper and lower portions of each of said compartments, a metal structure having an outer surface in the form of an oxidation catalyst located in said duct, fan means for recirculating atmosphere from both of said compartments through said duct in contact with said oxidation catalyst and back to said compartments, said compartments each being pro- '7 vided with an inlet opening for outside air, said duct being provided with a discharge opening for discharging atmosphere to the outside, means for heating said ovens and said metal structure, and control means for shutting off the circulation between either of said compartments and said duct.

References Cited in the file of this patent UNITED STATES PATENTS 1,884,746 Kline Oct. 25, 1932 s Frazer Nov. 14, 1933 Hofierbert Nov. 2, 1937 hlaxson Dec. 6, 1949 Scott Dec. 13, 1949 Weintrob et a1. Jan. 10, 1950 Cline June 13, 1950 Suter Nov. 10, 1953 Fries Jan. 3, 1956 

